>> the sign of a professional, john. a good professional will lever never let you know if they are lip-synching. here is the deal. beyonce can sing live. we have been to her concerts, seen plenty of performances. for an historic event, if she used to use prerecorded vocals, we give her a pass. just like whitney houston, neil diamond, and others have used at the super bowl. there are certain elements -- your voice is an instrument. you have laryng inclaryngitis. >> she took her earpiece out, does that indicate anything? >> ever seen janet jackson or britney spears, they have earpieces and lip sync the entire show. you have to hear yourself and the music. for your mouth to be in sync for what's prerecorded. you have to make sure the sound is balanced out. >> if she did, she would be no way the first to do it. i saw millivanilla van ivan i millivanilli in concert. >> here is the difference. millivanilli lip synced to someone else's voice. beyonce sang to her own. let's not forget, four years ago, cellist yo-yo ma did a prer